Beyond the Ariel

[Variac]

Oooooh those have some great points- including great stability. Here in San Francisco you have to consider the next 'quake.

fiacono, I wasn't proposing the 15"Eminence for the low bass drivers but as a single driver to cancel out the open baffle roll off of the 12" That's why its response to over 2k is relevant. Lynn has mentioned this idea as central to many od the designs he's proposed but mostly using another 12"

John,
I believe the Eminence curves more than I do many manufacturer's. Eminence seems perfectly happy to post horrific (for our needs) curves for some of their other drivers...... The 10" and 12" in the same series aren't quite as good for example. Also this is the series ll which seems to be smoother than the original...

Lynn,
Well, there is one very small good thing about your condition- it made you post here and get our brains whirring!! Thank You.
Also the various versions you have sketched out in words seem to be in keeping with most of your original goals, but refecting what is available in the real world, and some good original thought. I like 'em all, and by the time they are built, you will not only have a favorite I'll bet, but I also suspect that there will be some favorite drivers swapped between the various models, resulting in even better designs.

[Cappy]

Russell,

Now that is interesting. And a BMS compression driver to boot.

More pictures:

http://www.audioxsell.com/community/...ld-Physics.htm

http://db.audioasylum.com/cgi/m.mpl?...cs&r=&session=

[SunRa]

Hello Mr. Olson,

great news from your medical report. I had to walk from hospital to hospital for the past 2 weeks helping someone dear for some investigations which concluded in a surgical intervention and I know it's not easy.

Now the hardest part is past, I guess the next 6 weeks will go lighting fast and you'll be completely recovered soon.


Regarding the design you are proposing: As I recall the 12" midbas unit, midrange and the woofer are handling the 2kHz- down region. Even if under 200Hz (where the 12" coax or midrange roll-of starts) the frequency isn't as easy to position as in the HF, won't apear some audible anomalies because of the renedring of the same acoustic material from diferent units (the 12" and the 15")?

[Lynn Olson]

Originally posted by Russell Dawkins
Lynn,
glad to hear your recovery is on track, congratulations!

I wonder if you ever got to hear or see the Emerald Physics DSP controlled dipole.
I was just looking through some old correspondence and came up with these details as to the components used and the crossover frequencies. Thought you might be interested:

(1) BMS 4552 1" compression driver (1250Hz-20kHz)
(1) DDS ENG1 90 degree waveguide mated to BMS
(2) Ciare 8-64 8" midranges in parallel (150Hz-1250Hz)
(3) Eminence Alpha 15A woofers in parallel (<150Hz)
(1) dbx 260 DSP controller (for both channels)

Bass panel is 60" H x 24"W
Mid/treble panel is 60"H x 15"W
Both panel are connected together by 8 solid aluminum rods 18" long and 2" diameter.

If you are not familiar with this speaker, here's a picture (note the current design has 3 not 4 15" bass drivers, and the bass drivers are all in one panel which is attached to the mid/hi panel, logically, so one piece per side, not two):
http://tinyurl.com/32pgwe

Quite a few people thought these were the best or nearly the best sound at the last RMAF.

Huh, I was at the RMAF, but didn't see or hear of the Emerald Physics room. There were some hundred-plus rooms, and that's one I missed. I would have liked to have heard the system, though - I'm fond of dipoles.

I made the mistake of exhibiting the Karna amplifiers at last year's RMAF, but it was hardly worth the effort of transporting four fragile wood-framed chassis and a separate box of tubes and cables since they were only used in-system for a few hours. Baby-sitting the quartet of chassis and missing much of the RMAF show just wasn't worth it. For the next show, I'll do what I did the first year I went to the RMAF - bring only myself and a camera, and enjoy the show and the socializing.

The Emerald Physics speaker seems well-designed from what's in the pictures, although I would have thrown some baffle asymmetry in there to minimize standing waves. I'm also surprised to see a vertical stack of deep-bass woofers - just lay the woofer panel on its side, to get the enormous benefits of the mutual reflection of floor-coupling. They're already using room-EQ, so why not make the room work for you?

Originally posted by SunRa

Regarding the design you are proposing: As I recall the 12" midbass unit, midrange and the woofer are handling the 2kHz- down region. Even if under 200Hz (where the 12" coax or midrange roll-of starts) the frequency isn't as easy to position as in the HF, won't apear some audible anomalies because of the renedring of the same acoustic material from diferent units (the 12" and the 15")?

I met Stan Ricker, the famous recording engineer, back in my Positive Feedback technical editor days, at one of our conclaves in Portland, Oregon. He said something I never forgot: he preferred monitor speakers with two dissimilar woofers operating in parallel, both covering the bass frequencies. Why?

Well, all woofers have a "tone color" - none are neutral. Not only that, the tonal palette reproduced by any one woofer has limits - there are some tone colors it just can't reproduce. So not only are there "additive" colorations, which overlay the sonic presentation, but "subtractive" ones, which limit the range of tonal colors. All drivers have these properties - they add colors that aren't there, but worse, there are certain timbral characters that just don't come through at all, or are grossly altered by the transducers.

This was the point made by Stan: it's an important matter when a studio monitor fails to reproduce certain tone colors - it leads to serious errors in the mixdown, and has consequences in the marketplace. Interestingly, recording professionals can "work around" known colorations - but when the monitor overlooks things, that's more serious.

Anyway, Stan's workaround for this is using dissimilar woofers in parallel. I was surprised when I first heard this, but it makes sense. All bass drivers operate in the piston region - they are inherently flat, so no response (and phase) variations arise. The tonal variations are much subtler - artifacts of magnetic design, differences in cone construction, etc. Since all the drivers are in phase-lock (due to piston-band operation), and the wavelengths are quite long, there aren't any issues of mutual cancellation that would arise at higher frequencies.

Dissimilar drivers working in parallel at higher frequencies would be troublesome because of frequency response variations, the associated phase variations, and the way these phase differences steer the polar pattern up and down. That would very undesirable - it's hard enough to manage the phase angles of a crossover between two different drivers, never mind more!

At very low frequencies spanning the region between the highest and lowest Fs of the set of drivers, yes, then they spread apart, but the greatest phase spread between any of them is well under 90 degrees, probably more like 30~40 degrees. At frequencies below the lowest Fs, the drivers return to mutual phase-lock.

So the dissimilar drivers all working in parallel is borrowed from Stan Ricker - it took me a few weeks to remember where the idea came from. I've re-applied it to a dipole, instead of a closed box sharing a common volume. Reading the Tone Tubby site, where they recommend combining two Alnico 12" TTs with two ceramic 12" TTs in a single open-back cabinet, also stimulated that line of thought. What they were saying about a wider gamut of tone colors pretty much echoed what Stan Ricker said many years ago.

[Russell Dawkins]

Too bad you didn't hear the Emerald Physics speaker.

A friend whose judgement I trust and who has the good judgement to have lived with Beveridges for 20+ years, but who is on an intensive search for something new and has heard (and liked, but not loved) the Orions and the Apollos and almost everything else of note had this to say about the Emerald Physics effort:

"....Case in point is the Emerald Physics speakers at this years RMAF. Here is a speaker that is selling for $6750 and could easily be compared to cost-no-object esoterica in terms of sound quality. People were handing him deposits even though he has yet to produce a single production unit. You'd throw S****s (a highly regarded waveguide 2 way) out the window after listening to the Emerald Physics--or at least, everyone I know around here would....."

Too bad something seems to be amiss, in that the website which was supposed to be up in November last is not yet active.
http://www.emeraldphysics.com/

As far as dissimilar woofers - reminds me of Nesterovic (sp?) who did a similar thing in the early 70's when he was with SpeakerLab of Seattle, but using, if i remember a 12 and a 10 in a sealed box. Could be wrong about the details.

Speaking further of a gamut of tone colors - anyone old enough to remember the "Sweet Sixteen" - a sixteen speaker wall of sound box published as a DIY project by Popular Electronics in about 1962 (!!)

[Lynn Olson]

Originally posted by Russell Dawkins

"....Case in point is the Emerald Physics speakers at this years RMAF. Here is a speaker that is selling for $6750 and could easily be compared to cost-no-object esoterica in terms of sound quality. People were handing him deposits even though he has yet to produce a single production unit. You'd throw S****s (a highly regarded waveguide 2 way) out the window after listening to the Emerald Physics--or at least, everyone I know around here would....."

Speaking further of a gamut of tone colors - anyone old enough to remember the "Sweet Sixteen" - a sixteen speaker wall of sound box published as a DIY project by Popular Electronics in about 1962 (!!)

Be interesting to know the name of the "S****s" speaker. (The Summa?) I only guessed the name of the Verity in that other forum because I noticed the name of the Gif file was "Verity.gif".

Yes, I remember reading that article - boy, do I date myself. That was back when I was going to high school in Hong Kong (King George the Fifth) and faithfully read every issue of Analog Science Fiction (back when it was good), Popular Electronics, and Wireless World as soon as they appeared on the newstand at the Star Ferry. (Back then, there was no tunnel between Hong Kong Island and Kowloon, and you had to take the Star Ferry each weekday to get to school.)

Wow, memories abound. Buying the Pentax Spotmatic a month after it came out, visiting The Radio People hifi store every month, and hearing the Quad ESL57 for the first time, along with matching Quad electronics. Never did persuade my dad to get the good stuff, he got a Pioneer low-watt receiver and no-name Hong Kong made speakers with no bass at all. I compensated by blowing the money I should have spent on a car when I went to college (in Los Angeles, of all places!) and wasting it on a pretty fancy stereo system.

[planet10]

Originally posted by Russell Dawkins
Speaking further of a gamut of tone colors - anyone old enough to remember the "Sweet Sixteen" - a sixteen speaker wall of sound box published as a DIY project by Popular Electronics in about 1962 (!!)

April 1961

I had a pair of those thru here. They aren't very good... Sweet 16 Articles

dave

[Lynn Olson]

Originally posted by planet10

I had a pair of those thru here. They aren't very good... Sweet 16 Articles

dave

I bet. They probably sound just like a really big transistor-radio speaker. The miracle of higher efficiency (in the bass where the drivers are in-phase with each other) isn't going to do much for all the cone break-up at higher frequencies.

It does make you think about the genesis of the B--- 901, though. Ol' Amar did pretty well off that one. Kind of like Seattle Computer Products, QDOS, and Mr. Bill G.

[jamikl]

Has anybody interested in this thread read US Patent US 6,993,141 B2. I don't even remember whether I saw it on this thread or the other similar thread. May have found it whilst surfing other patents. Does this type of crossover have relevance for the system under discussion - seems to me it would have. I don't know much at all about the electronics side of things but could it be done as a PLLXO where I understand the components could be a lot smaller and maybe easier to obtain. Any comment welcome.
jamikl

[Lynn Olson]

Just a little tid-bit here, I'll write it quick before signing off this evening.

I could be 100% wrong on the "dissimilar woofers working in parallel" thing. The test, obviously, is in the listening. If the bass is a murky mess when all the woofers are hooked up together, well, so much for that idea. Fortunately, this is easy to test.

Start by building the baffle with the mounting holes for the 12" midbass and 15" bass drivers covered with circular wood disks the same size as the intended drivers. Spend a fair amount of time listening to the system with the single widerange driver. I advise listening in stereo to get acquainted with its spatial properties, not just the tone. Choose the widerange driver you like best. That's what I'll do.

Go forward and design the MF/HF crossover for either the ribbon or the BMS+horn, as you wish, measuring and listening as you go. This will give you a high-quality system with response from 160 ~ 200 Hz on up. Bass will be thin but very quick and resolved.

Now ... remove the temporary wood disk and add the midbass driver with its 160 ~ 250 Hz lowpass filter, in parallel with the wideband driver (and sharing its lowpass filter). How's the bass? More of it, of course, but how's the clarity and most of all, the tonal quality? This is the make or break question. Is it better with the dissimilar driver or the same driver as the widerange driver? Expensive, I know, but I'm afraid this can only be settled by audition.

Repeat for the bass driver - same test, using clarity and tonal beauty as the criteria. Don't zero in on room abberations too much at this point - this is the frequency range where EQ is desirable, and you don't want to monkey with the speaker to fix the room.

Note the key concept is to select the widerange driver and build outward, starting with the tweeter. This way you can judge your progress as you go, and not lose sight of your direction as you progress forward. I spent a lot of time listening to drivers on a baffle before I chose the 5.5" Vifa for the Ariels - I advise the same.

You want all the drivers to complement the wideband driver, not the other way around, since it is the center of the spectrum, and will determine the character of the entire speaker. You are adding bandwidth to the widerange driver, selecting complementary drivers (and crossovers) as you go. At no point do you want to lose the essential character you started with - if you do, go back, and re-think the crossovers or the choice of additional drivers.